Although it is well very established, for the classic experiments, which are the factors that limit the production, the operation of the plant in the reproductive phase that involves a compound so much relationship between organs source and fotossintatos drain as of the metabolism of the nitrogen in both types of organs, it remains unclear. Like this being, in the pollination phase different proportions of leaves were imposed (% of source) and of grains (% of drain) in corn plants to study the effect of these treatments on the behavior of nitrogen metabolism in grains, leaves and stems, in different stages during reproductive phase of the culture and your relationships with the production of dry mass, development of grains, as well as development and senescence of leaves. Enzymes activity were evaluated (NR, TGO and TGP), the level of main metabolites (N-total, N-nitrate, free amino acids and soluble protein) in the leaves, in the stems and in the grains in formation, as well as the reflexes of these varied on the agronomic characteristics (mass evaporates of leaves stems and grains), to the 2, 10, 20 and 30 days after the pollination (dap). The results of the present work allowed to clear that the activity of the nitrate reductase in the leaf was not affected by the alterations in the source proportions and photoassimilated drain. The levels of N-total, N-nitrate and free N-amino acids, in the leaves, stems and endosperms were more intensely affected the more drastic they were the reductions of leaves or grains. The reductions of the source and drain promoted significant increases in the levels of N-total, N-nitrate and free N-amino acids in the analyzed remaining parts. The soluble protein concentration was more affected in the grains, where the largest values were found to the 10 dap, in the treatments without leaves and grains... (Complete abstract, click eletronic address below).